Add /etc/fstab to initramfs (#447)

That way it can mount a root volume with mountpoint=legacy.

src/zfs-utils/zfs-utils.initcpio.hook

@@ -129,7 +129,7 @@ zfs_mount_handler () {
 
     local node="$1"
     local rootmnt=$(zfs get -H -o value mountpoint "${ZFS_DATASET}")
-    local tab_file="${node}/etc/fstab"
+    local tab_file="/etc/fstab"
     local zfs_datasets="$(zfs list -H -o name -t filesystem -r ${ZFS_DATASET})"
 
     # Mount the root, and any child datasets

src/zfs-utils/zfs-utils.initcpio.install

@@ -41,6 +41,7 @@ build() {
 
     [[ -f /etc/zfs/zpool.cache ]] && cp "/etc/zfs/zpool.cache" "${BUILDROOT}/etc/zfs/zpool.cache.org"
     [[ -f /etc/modprobe.d/zfs.conf ]] && add_file "/etc/modprobe.d/zfs.conf"
+    [[ -f /etc/fstab ]] && add_file "/etc/fstab"
 }
 
 help() {